Prison gangs are becoming the custodians of order behind bars and on the streets Books such as Christian Parenti's, Lockdown America, and David Skarbek's,The Social Order of the Underworld posit the idea that prison gangs such as the Aryan Nation, The Mexican Mafia, The Black Guerrilla Family, and others serve a useful function. Prison gangs in an effort to keep their business interests going want order. Multiple gangs keep the other gangs in check. With the US having one of, if not the highest rate of incarceration it may be impossible to maintain any semblance of order without the gangs.
The Mexican Mafia has significant operational control only within prisons, yet manages to tax street gangs at rates of 10-30% of revenues. It has become a kind of government. A PDF of the corresponding journal article exists here.